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                [Poi1999]洞穴攀行                </h1>
                <p>时间限制：1s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><div>
<div>洞穴学者在Byte Mountain的Grate Cave里组织了一次训练。训练中，每一位洞穴学者要从最高的一个室到达最底下的一个室。他们只能向下走。一条路上每一个连续的室都要比它的前一个低。此外，每一个洞穴学者都要从最高的室出发，沿不同的路走到最低的室。</div>
<div>限制：</div>
<div>1.起点连接的通道同一时间只能容纳一个人通过</div>
<div>2.终点连接的通道同一时间只能容纳一个人通过</div>
<div>3.其他边都很宽敞，同一时间可以容纳无限多的人</div>
<div>问：可以有多少个人同时参加训练？</div>
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<p></p></p><hr/><h3>输入格式</h3><p><div>&nbsp;</div>
<div style="text-indent: 21.75pt"><span style="font-size: medium">第一行有一个整数n(2&lt;=n&lt;=200)，等于洞穴中室的个数。用1~n给室标号，号码越大就在越下面。最高的室记为1，最低的室记为n。以下的n-1行是对通道的描述。第I+1行包含了与第I个室有通道的室（只有比标号比I大的室）。这一行中的第一个数是m,0<i>&lt;=</i>m<i>&lt;=</i>(n-i+1)，表示被描述的通道的个数。接着的m个数字是与第I个室有通道的室的编号。</span></div>
<div><span style="font-size: medium">&nbsp;</span></div></p><hr/><h3>输出格式</h3><p><div>&nbsp;</div>
<div style="text-indent: 21.75pt"><span style="font-size: medium">输出一个整数。它等于可以同时参加训练的洞穴学者的最大人数。</span></div>
<div><span style="font-size: medium">&nbsp;</span></div></p><hr/><h3>样例输入</h3><pre>12
4 3 4 2 5
1 8
2 9 7
2 6 11
1 8
2 9 10
2 10 11
1 12
2 10 12
1 12
1 12</pre><hr/><h3>样例输出</h3><pre>3</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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